All done... i got the AC fixed... I will put a thread about the problem and the steps of solving it...


Thanks to the guys above me... getting the new part and replacing the old one was an easy ride

 

On my 2003 Honda Accord EX 6 cyl sedan the "resistor" (really a controller) is located behind the snap-on under dash panel on the passenger side. It is affixed to the fire wall towards the driver's side corner of the snap-on panel with two Phillips head screws.

After pricing a new unit (~$85) I wondered what was inside the unit. I opened it be prying back the four tabs that holds it together. Inside is a little circuit board. I used a solder removal iron (~$12 at Radio Shack) to unsolder the three leads to the heat sinked power transistor (I think) and the two smaller leads to a thermal fuse clamped to the heat sink with the same screw that holds the power transistor to the sink. The fuse (rated at 2 AMPS and 114 C) had no continuity so was burned out. I replaced it with a $1.60 thermal fuse rated for 117 C purchased from a local electronic supply shop. (The 2 AMP rating on the original fuse should not be an issue so long as the replacement fuse will carry at least 2 AMPS. If my new one gets hotter than 117 C, it will melt and interrupt the circuit and power to the fan.) I resoldered and reassembled the unit making sure the fuse was coated well with thermal heat sink compound to assure good thermal connection with the sink. The entire job took about 20 minutes. Everything works fine again!


UPDATE - Make that $15.00

After a short time the power transistor (a high speed switch) burned out in the blower control unit. The blower then ran at full speed all the time the ignition switch was on. (The thermostatic control still worked.) In retrospect it seems the reason the thermal fuse burned out intially was becuase of a failing power transistor. For $15 I replaced the high speed switch (power transistor) with the recommended replacment item (NTE 2920 MOSFET N-Ch, Enhancement Mode High Speed Switch) since the original item (2SK2313) is no longer available. I had the local electronics supplier order it, but it is available from "Audio Lab of Ga" and other places. A nearly exact thermal fuse replacement is available from Digi-Key (see part # P10907-ND).

I believe this information also appears elsewhere in the site (DIY): Search
"2004 CRV :: AC Stopped working :: Replace Transistor / Thermal cutoff?",
which coincidentally is posted by another Stan (StanStr). There are excellent pictures there.

 

Nice post. If you had some pics we could put it as a DIY.

 

Ok so my blower motor on my 2004 Accord EX was shot, I could get it to run a little if I hit it but not well. But the A/C would work intermittently while I was waiting for the part to come in and replace the blower. I replaced the blower but now the A/C doesn't work. The compressor does not cycle. My best guess is the resistor is shot from the blower not running well for a couple weeks. Is this the best place to start looking for the new problem or is there something else I should do first. I tried to look at the relays under the hood but unlike a fuse which you can tell if it is shot these are black.

 

Thank you, thank you, thank you! This didn't go as smoothly for me as it did for you, but ultimately worked out. My problems might be a helpful cautionary tale for others who want to try this.

It's in the upper 90's here in NJ and I don't have any electronics supply houses nearby. Ordering a thermal resister just like the bad one would take a while and I wanted to solve my problem FAST - partly because it's HOT and partly because I figure fuses go for a reason and if I replace the fuse and it blows again, I have other issues that will need to be solved first.

It turns out that Radio Shack carries a few thermal fuses include a (nominally) 127C fuse. http://www.radioshack.com/product/in...ductId=2062259 Yes, it's more than the 114C fuse I'd be replacing, but it's a risk I was willing to take. (And, my package contained fuses labelled 133C. There's a cute disclaimer on the package about how item may not match the package specs or something like that.)

These fuses, however, are in a metal package which is not isolated from one of the leads. This was the source of my problem. They are also slightly larger in diameter and the leaders are a thicker. The thicker leads also required some cutting of the plastic guides that hold the fuse in place.

As it turned out, once I screwed the fuse clamp and the transistor back on to the heat sink, the barrel of the fuse made contact with ground, shorting both leads to ground. (That is until the fuse subsequently blew. Then only the one attached to the metal body of the fuse was shorted.)

I knew *something* was wrong when I reconnected my reassembled module and the fan came on full speed regardless of the switch position (even off). And the A/C compressor would *not* come on, regardless of fan speed position, even though the A/C light was on.

And the module got HOT, so of course the fuse blew. But the fan kept going....

So....back to RadioShack for another fuse.

This time, I covered the body with some heat shrink tubing and reassembled. And tested for shorts every which way before trying out the reassembled module in the car. I know I don't have the best thermal conductivity - and a higher temperature fuse, too. But I'm reasonably confident that fuse will still blow before anything catches fire.

If I can get my hands on a more appropriate fuse, I'll redo it for a third time. Sure beats $85 for the part at the dealer or $60 online and a week's wait!

Now I just have to find the snake in my car....

 

hondadude,

Can't seem to pull up the image you posted. Can you repost? I'm trying to verify the location of the resistor.

Thank you,
hockeyrulz

 

Please read the first post at the top of the gen tech help forum. Especially #1.

Here is a link to an 03.

honda-tech.com/showthread.php?t=2041582

Also some pics in one of our threads
https://www.hondaaccordforum.com/for...ad.php?t=34292

 

Many thanks,

My Accord is a 2004, but it looks like the resistor is attached to the blower motor--wasn't looking there although I did see the wires and connector. I'll get under the dash again today to have a look.

Thanks for all your help on these forums. I'm not a mechanically-inclined person, but I'm fairly good at figuring things out in general. I'd rather borrow a soldering iron and buy a $1.60 thermal fuse than pay $85 for the replacement.

I'll let you know how it goes.

Thanks!

 

Have you determined the fan-speed controller is bad? As opposed to wiring problems?

Check out this thread, posts # 15 & 16.
https://www.hondaaccordforum.com/for...ad.php?t=33007

 

I swapped the relays and the blower fan still did not come on. That should eliminate that possibility unless the other relay is bad as well, right?